1. Field of the Invention
The invention relates to a rotor for an electric machine, e.g. an electricity generator or an electric motor, comprising a base body and a plurality of support bodies that are fixed on the base body and support permanent magnets.
2. Discussion of the Prior Art
The structure of such rotors has been known for a long time. For an equally long period there have been problems concerning fastening the permanent magnets, that are usually bonded to support bodies, on the rotor's base body. For the task of assembly, special safety measures are taken for the personnel, it having to be ensured in particular on account of the considerable magnetic fields produced by the permanent magnets that only non-magnetic materials are introduced into the work rooms and in particular only non-magnetic tools are used. In addition the installation takes place in clean rooms so as to rule out any contamination that could adversely affect the operation of the electric machines to be assembled.
When assembling the permanent magnets on the outer circumference of the rotor's base body the problem exists in particular that magnets arranged on neighbouring support bodies exert strong attractive and repulsive forces on each other and thus make assembly difficult to a considerable extent. During operation of the machine there are also centrifugal forces that act on the support bodies in addition to the magnetic forces, making it necessary to produce an extremely safe and durable connection between the permanent magnets and/or the support bodies and the base body of the rotor.
The connection between the rotor's base body and the support body is usually made by means of a positively locking connection where a groove on the shape of a dovetail is machined in the base body of the rotor, into which a dovetail-shaped pin formed on the base bodies can be introduced. Such designs are for example known from EP 1 439 626 A1 and DE 197 05 432 A1.
Even though this design ensures that the support bodies and thus the permanent magnets fitted thereon can be attached successively by pushing into the groove on the rotor's base body, such that they can be loaded in each case. However the implementation of this connection is very labour consuming and requires a high degree of precision for the necessary manufacturing tolerances to be kept. The manufacture of the rotors is therefore also very cost intensive.